Tunica County Sheriff KC Hamp tells WREG-TV that a body matching the description of Cortez Moore was spotted by a helicopter on Wednesday, floating in the river near Dundee.
The body was sent to Mississippi's crime lab in Pearl for official identification.
Moore has been missing since Sunday, after an SUV driven by 29-year-old Symphony Wilson plunged into the river.
Hamp says Wilson dropped a relative at work at a casino. Her body was found Monday.
Another child inside, 5-year-old Brenilah Moore, was found Tuesday. Wilson wasn't the children's mother.
It remains unclear why the SUV left the road and entered the water.
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